This invention generally concerns online presentation broadcasting over a network, and more particularly, broadcast of a presentation that includes both a live portion and a predefined portion over the Internet.
Online presentation broadcast technology allows people to xe2x80x9cattendxe2x80x9d a virtual presentation broadcast by broadcasting the presentation over a network to computers that are accessible to the attendees. Recent advancements in networking and online presentation broadcasting technology have led to a rapid increase in the use of such virtual presentation broadcasts, particularly over intranets within large corporations. Of course, the advantages of virtual presentation broadcasts are perhaps best realized over the Internet, which can reach an even greater audience. While these advancements have been dramatic, the ease of use in presenting and receiving such broadcasts have not kept pace.
A typical online broadcast of a presentation is performed in the following manner. A presentation designer, or design team, creates a presentation, which typically comprises a plurality of slides, including text and/or graphic content. The presenter then conducts a xe2x80x9clivexe2x80x9d performance of the presentation, which is recorded using one or more video cameras with microphones. The recorded presentation generally consists of video and audio content that is recorded on a magnetic tape media using an analog encoding format. For example, conventional television signals are encoded using one of three standard formats: National Television System Committee (NTSCxe2x80x94used in North America), Phase Alternating Line (PAL), or Sequential Color and Memory (SECAM). These standards define encoding schemes for mechanisms that can be used to encode and/or decode analog audio and video broadcasts or tape recordings. For instance, a camcorder designed for use in the United States will encode video and audio content using the NTSC analog format, so that the recorded video and audio content can be viewed on a conventional television when it is played on the camcorder (or other playback equipment).
Although the foregoing analog recording technology and encoding formats have worked well for many years, recordings that use these formats cannot be directly used to transmit audio and/or video content via an online broadcast, since computer networks cannot transfer content that is in an analog format. This problem is addressed by using special audio and video xe2x80x9ccapturexe2x80x9d equipment, which converts the analog signals produced by audio and video recording (and broadcasting) equipment into a digital format, using a special type of encoding scheme and/or device called a codec. The term codec, which is an abbreviated form of coder/decoder, actually originated in the field of analog communications long before the first bit was transmitted digitally. NTSC, PAL, and SECAM are examples of analog codecs used in television broadcasting.
Through the use of one or more codecs, the capture equipment converts an analog recording (or original broadcast signal) into a digital format in the following manner. Typically, the recording is converted into a digital format by using a computer that includes one or more audio and/or video capture cards that receive an analog signal produced by the playback equipment (or which is directly produced by equipment such as a microphone or television broadcast camera) during the live presentation and converts it into a digital format using a particular codec that the cards are designed to implement. Such cards generally employ a special chip that is programmed with logic for converting an input analog signal to an encoded digital signal of a predetermined format, preferably in real-time.
Under Microsoft WINDOWS(trademark) operating systems, codecs are usually implemented to be ACM (Audio Compression Manager)- or VCM (Video Compression Manager)-compatible, so that the output of the codecs can be directly read and used by ACM- and VCM-compatible software. Various ACM- and VCM-compatible codecs are used to produce audio and/or video content in several different formats, including .wav, avi. and .mov file formats, as well as MPEG and MP3 formats.
Once the audio and/or video content of the presentation is converted into an appropriate digital format, it can be sent to an online audience. In the past, this has been done after a request from each audience member causes the file or files comprising the content of the presentation to be downloaded to their own computers. Once the file is downloaded, the presentation can be viewed by xe2x80x9cplayingxe2x80x9d the file with an appropriate codec player, such as Microsoft Corporation""s WINDOWS MEDIA PLAYER(trademark), or the QUICKTIME(trademark) player developed by the Apple Computer Corporation. In order to view a presentation in this manner, it is necessary that the appropriate player be already installed on the viewer""s computer.
In addition to viewing presentations in the forgoing manner, recent advancements in streaming format technology have made it possible to receive audio and video content via live broadcasts over the Internet and other network environments. As opposed to conventional network file transfer schemes, streaming format technology allows content to be continuously xe2x80x9cstreamedxe2x80x9d to one or more computers over a network rather than being first downloaded as a file. A typical example illustrating the use of streaming format technology is a live Internet concert, in which audio and video equipment at the performance site produce signals that are converted into a digital format in real- or near-real-time (or are already in a digital format if digital camera equipment is used), and the digital content is converted into an appropriate streaming format and broadcast to a large audience accessing the concert via an Internet Web page. In addition to concerts, streaming technology is presently used for broadcasting other types of live events, including presentations.
Although the foregoing schemes have greatly advanced the use of online broadcasting, they both have significant drawbacks when they are used for broadcasting an online presentation. Notably, when employing either of these methods, the screen area occupied by the video image seen by the online audience is quite small, often making the content of the presentation, especially presentation slides, difficult to view. The relatively small size of the video image is generally due to bandwidth and compression technology limitations, as well as quality considerations. For example, a video frame update rate of 30 frames per second (fps) is generally believed to be the minimum acceptable frame rate for rendering objects that move at a medium rate of motion, such as a person giving a live presentation. In addition, 30 fps is the accepted rate in the NTSC television standard, so most people are accustomed to viewing video content at this frame rate. Suppose that under a worst case scenario, the maximum bandwidth connection available to a person in the audience viewing a presentation is 28.8 Kilobits per second (Kbps). In order to handle this worst case scenario and maintain a frame rate of 30 fps, the video content and audio content of the presentation should be divided into 22 Kbps and 6 Kbps portions, respectively. Under Microsoft Corporation""s WINDOWS(trademark) media technology, the 22 Kbps video content portion corresponds to a 22 Kilobit WINDOWS(trademark) media encoder template that produces a video image of only 160xc3x97120 pixels, while the audio content portion is encoded by an appropriate codec as a monophonic audio signal at 6 Kbps (corresponding to a sampling rate of 8 KHz). When displayed on many of today""s computer monitors, which typically provide a display resolution of 1024xc3x97768 pixels or greater, a video image of 160xc3x97120 pixels only occupies a small portion of the monitor""s available display area. Therefore, a presentation slide that was originally designed using a monitor""s entire display area will be difficult, if not impossible, to read. Accordingly, a live presentation broadcast that produces such a small video image will be of little value to most audience members.
A similar problem exists when viewing a presentation that is enabled through the use of downloaded files. In order to conserve file size, as well as for other reasons, the display area of an image in a video media player is again generally only a fraction of the total display area of a monitor. As a result, this method also does not adequately display presentation slide images.
It would therefore be desirable to provide a system and method that enables an online audience to view a presentation without encountering the limitations of the foregoing conventional methods. Ideally, an acceptable solution to this problem should produce a composite display image replicating visual aspects of a live presentation that is displayed in a small portion of a viewer""s display screen, with graphic content corresponding to the presentation slides of the presentation occupying the majority of the display screen area, thereby enabling the audience viewing the presentation on the computer displays to clearly see the presentation slides. At the same time, the system should replicate the audio content of the live presentation in synchrony with display of the presentation slides. In addition, it would be desirable to enable a presenter to broadcast such an online presentation with minimal intervention and setup.
The present invention addresses many of the shortcomings associated with previous online presentation broadcasting schemes by providing a system and a method that greatly improve the quality of the presentation content made available to an online viewing audience and facilitate the start of the presentation. The system leverages many of the features of Microsoft Corporation""s NETSHOW(trademark) server technology, along with Microsoft Corporation""s POWERPOINT(trademark) 2000 presentation design application program to enable a presenter to broadcast a presentation to an online audience over a computer network, such as an intranet or the Internet. The system enables a live presentation comprising a plurality of presentation slides, and audio and (optionally) visual content to be broadcast to a plurality of receiving computers over a network, so that the presentation slides are displayed, and the audio and visual content are replicated on the receiving computers in synchrony with the live presentation.
According to a first aspect of the invention, a method is provided for broadcasting a live presentation from a presentation broadcast source to a plurality of receiving computers linked in communication with the presentation broadcast source across a computer network. The live presentation includes a predefined content portion comprising a plurality of presentation slides that are displayed in response to slide triggering events during the live presentation, and a live portion comprising live audio and/or visual content performed in conjunction with the broadcast of the presentation slides. In some instances, the live content will comprise an audio narrative provided by a presenter during the presentation. In other instances, the live content will also comprise visual aspects of the presentation, such as a view of the presenter during the live presentation. These visual aspects are replicated on the plurality of receiving computers, thereby enhancing the online presentation. The predefined content comprising the plurality of slides is sent over the computer network to the plurality of receiving computers. Preferably, data corresponding to the plurality of presentation slides are saved to one or more HTML files, and the one or more HTML files are broadcast to the plurality of receiving computers prior to the start of the presentation so that they are cached by a browser application program (preferably Microsoft Corporation""s INTERNET EXPLORER(trademark) browser) running on each of the receiving computers. A data stream comprising data corresponding to the live portion of the presentation is generated and streamed to the plurality of receiving computers via the computer network. Preferably, the data stream is produced by encoding digital audio and video signals respectively produced by audio and video capture equipment into an active streaming format (ASF), which is suitable for streaming data over computer networks such as the Internet.
As each of the slide triggering events occurs, a corresponding slide display command for controlling display of the presentation slides on the plurality of receiving computers is generated and streamed to the receiving computers. The slide display commands comprise HTML script commands that control the display of the plurality of presentation slides, so that the slides are displayed on the receiving computers in synchrony with their display during the live presentation. As the data stream is received, it is decoded by a media player (preferably Microsoft Corporation""s WINDOWS(trademark) Media Player) running on the plurality of receiving computers so as to replicate the live portion of the presentation on the receiving computers in synchrony with the display of the presentation slides. Thus, the live presentation is replicated on the plurality of receiving computers, enabling both small and large online audiences to xe2x80x9cattendxe2x80x9d the presentation at remote locations.
According to other aspects of the invention, a system for implementing the foregoing method is provided. According to a first preferred configuration, the system comprises a local computer connected to at least one receiving computer across a computer network. The presentation preferably is designed and presented using the POWERPOINT 2000(trademark) application program, a copy of which is running on the local computer. During the presentation, a presenter advances through the plurality of presentation slides by issuing slide triggering events to the POWERPOINT 2000 program. In response to the slide triggering events, successive slides in the presentation are displayed and/or animated, and slide display commands for triggering a synchronized display and/or animation on the receiving computers are generated. Preferably, the local computer also includes an audio capture subsystem, such as a high-performance sound card (or embedded sound system) connected to a microphone, so that the live audio aspect of the presentation is captured and processed, producing a corresponding digital audio signal. This digital audio signal, along with the slide display commands, is encoded into an ASF stream, and broadcast from the local computer to the receiving computers over the computer network. As the ASF stream is received, it is decoded by a media player module running on each receiving computer, thereby replicating the live content portion of the presentation in real-time (with a slight network delay). Since the slide display commands and encoded data corresponding to the live audio content are streamed to the receiving computers via the computer network in real-time, the plurality of presentation slides are displayed in synchrony with the replicated live audio content.
The foregoing system configuration may also include a video capture subsystem comprising a video camera and video capture circuit for producing a digital video signal corresponding to visual aspects of the presentation. The digital video signal is encoded into the ASF stream along with the digital audio signal, so that visual aspects of the presentation are replicated on the receiving computers.
A second preferred configuration of the system further comprises a NETSHOW(trademark) server that is linked in communication with the local computer and to the receiving computers. The NETSHOW(trademark) server, which is running Microsoft Corporation""s NETSHOW(trademark) server application program, may be a local server, or may be a third-party server linked in communication with the local computer via the Internet. The one or more HTML files comprising the presentation slides are sent from the local computer to the NETSHOW(trademark) server, which then broadcasts the files to the receiving computers, preferably using a multicast broadcast. The multicast broadcast is performed using a relatively high bandwidth (preferably corresponding to a substantial portion of the available bandwidth of the receiving computers), prior to the start of the presentation, to enable the HTML files to be cached by the browser application programs of the receiving computers. During the presentation, the ASF stream comprising the live content and the slide display commands are sent to the network server, which then broadcasts the ASF stream to the receiving computers. Also during the presentation, a lower bandwidth is used to multicast broadcast the HTML files, so that a portion of the available bandwidth of the receiving computers is used to receive any HTML files that were not received prior to the start of the presentation, while another portion of the available bandwidth is used to receive the streaming live content and slide display command.
A third preferred configuration of the system adds an encoding computer to the configuration of the preceding embodiment, so that the encoding computer is linked in communication with the local computer and the NETSHOW(trademark) server. Preferably, the encoding computer includes audio and video capture cards, which are respectively connected to a microphone and video camera for capturing live audio and visual aspects of the presentation. An encoding module (WINDOWS(trademark) Media Encoder) running on the encoding computer encodes the digital video and audio signals produced by the audio and video capture cards into an ASF stream, which is then sent to the NETSHOW(trademark) server. In addition, the slide display commands are sent from the local computer to the encoding computer, and the encoding module embeds the slide display commands into the ASF stream via insertion of a script in the ASF stream. The ASF stream is then broadcast to the receiving computers from the NETSHOW(trademark) server, as before.
According to still another aspect of the invention, a computer-readable medium is provided having computer readable instruction for performing the steps of the method, generally as described above.